What’s the different between a follicular unit and a follicle?

A follicle is a single hair that grows from a follicular unit, and a follicular unit can grow between 1 to 4 follicles.

It’s very unlikely that 1 follicular unit would only grow 1 follicle, usually grows more than 2. It also highly unlikely but possible that 1 follicular unit could grow more than 4 follicles.